feat(sqlsmith): generate ternary and variadic functions

[kwannoel]

I hereby agree to the terms of the Singularity Data, Inc. Contributor License Agreement.

What's changed and what's your intention?

• Generate remaining ternary function (split_part). Other ternary / quaternary functions are already generated in make_general_expr.
• Generate variadic functions. Identified these by looking at proto definition for ExprNode::Type.
  https://github.com/singularity-data/risingwave/blob/b596d4d80f725a2c2cb86b628104b334caf00f87/src/tests/sqlsmith/src/expr.rs#L170
• Leave out implicit cast from concat / concat_ws.
  This can be done as an improvement
  (already tracked Tracking Issue: Fix Sqlsmith workarounds / refinements / bugs #3896 ),
  but there are many unit / e2e test cases already for concat / concat_ws with implicit casts.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Documentation

If your pull request contains user-facing changes, please specify the types of the changes, and create a release note. Otherwise, please feel free to remove this section.

Types of user-facing changes

Please keep the types that apply to your changes, and remove those that do not apply.

• Installation and deployment
• Connector (sources & sinks)
• SQL commands, functions, and operators
• RisingWave cluster configuration changes
• Other (please specify in the release note below)

Release note

Please create a release note for your changes. In the release note, focus on the impact on users, and mention the environment or conditions where the impact may occur.

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Merging #4572 (b596d4d) into main (5796692) will increase coverage by 0.00%.
The diff coverage is 73.16%.

@@           Coverage Diff            @@
##             main    #4572    +/-   ##
========================================
  Coverage   74.23%   74.24%            
========================================
  Files         854      858     +4     
  Lines      127235   127347   +112     
========================================
+ Hits        94448    94543    +95     
- Misses      32787    32804    +17     

Flag	Coverage Δ
rust	74.24% <73.16%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/batch/src/rpc/service/task_service.rs	0.00% <0.00%> (ø)
src/common/src/util/mod.rs	0.00% <ø> (ø)
src/common/src/util/ordered/serde.rs	96.21% <ø> (ø)
src/compute/src/server.rs	0.00% <ø> (ø)
src/connector/src/source/kafka/mod.rs	0.00% <ø> (ø)
src/connector/src/source/kinesis/mod.rs	0.00% <ø> (ø)
src/connector/src/source/pulsar/mod.rs	0.00% <ø> (ø)
src/expr/src/expr/expr_unary.rs	68.86% <ø> (ø)
src/expr/src/vector_op/cast.rs	72.92% <0.00%> (-2.08%)	⬇️
src/frontend/src/binder/struct_field.rs	76.81% <ø> (ø)
... and 121 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more